U.S. patent number 7,682,851 [Application Number 11/500,867] was granted by the patent office on 2010-03-23 for organic light emitting display and manufacturing method thereof.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. Invention is credited to Young-tea Chun, Sung-kee Kang, Ick-hwan Ko, Ho-nyeon Lee, Young-gu Lee, Tae-sik Oh, Mi-Jeong Song.
United States Patent |
7,682,851 |
Lee , et al. |
March 23, 2010 |
Organic light emitting display and manufacturing method thereof
Abstract
An organic light emitting display and a manufacturing method
thereof include an improved encapsulation layer. The encapsulation
layer of the organic light emitting display includes an organic
layer uniformly covering bank portions and light emitting areas on
a substrate; and an inorganic layer formed thicker on the light
emitting areas than on the bank portions. In the organic light
emitting display, the inorganic layer is thick on the light
emitting area in which a sealing ability is required and the bank
portion is thin in order to provide flexibility. Therefore, the
encapsulation layer can be formed more easily compared to an
encapsulation layer on a device in which the organic layer and
inorganic layer are alternately formed at least 10 times.
Inventors: |
Lee; Young-gu (Seoul,
KR), Kang; Sung-kee (Seongnam-si, KR), Oh;
Tae-sik (Suwon-si, KR), Lee; Ho-nyeon
(Seongnam-si, KR), Ko; Ick-hwan (Seoul,
KR), Chun; Young-tea (Suwon-si, KR), Song;
Mi-Jeong (Suwon-si, KR) |
Assignee: |
Samsung Electronics Co., Ltd.
(KR)
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Family
ID: |
38161785 |
Appl.
No.: |
11/500,867 |
Filed: |
August 8, 2006 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070181872 A1 |
Aug 9, 2007 |
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Foreign Application Priority Data
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Feb 3, 2006 [KR] |
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10-2006-0010594 |
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Current U.S.
Class: |
438/26;
257/E33.059; 257/100 |
Current CPC
Class: |
H01L
27/3246 (20130101); H01L 51/5253 (20130101) |
Current International
Class: |
H01L
27/15 (20060101); H01L 29/26 (20060101); H01L
31/12 (20060101); H01L 33/00 (20060101) |
Field of
Search: |
;438/26
;257/100,E33.059 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1020030008818 |
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Jan 2003 |
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KR |
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Primary Examiner: Zarneke; David A
Assistant Examiner: Wagner; Jenny L
Attorney, Agent or Firm: Cantor Colburn LLP
Claims
What is claimed is:
1. An organic light emitting display comprising: a plurality of
light emitting areas between bank portions on a substrate; and an
encapsulation layer covering the light emitting areas and bank
portions, wherein each of the bank portions have a recessed shape
and are each disposed between the light emitting portions, and
wherein the encapsulation layer comprises: an organic layer
uniformly covering the bank portions and the light emitting areas;
and an inorganic layer formed thicker on the light emitting areas
than on the bank portions.
2. The organic light emitting display of claim 1, wherein the
inorganic layer comprises: a first inorganic film substantially
uniformly deposited on the organic layer; and a second inorganic
film deposited substantially only on the first inorganic film above
the light emitting areas.
3. The organic light emitting display of claim 1, wherein the
inorganic layer comprises: a first inorganic film deposited
substantially only on the organic layer above the light emitting
areas; and a second inorganic film uniformly deposited on the
organic layer and the first inorganic film.
4. The organic light emitting display of claim 1, wherein the
recessed shape results in a progressive reduction of a thickness of
each bank portion on opposing sides forming substantially a
V-shaped cut out.
5. The organic light emitting display of claim 1, wherein the
organic layer is formed of one of acrylic, methacrylic, polyester
polyethylene terephthalate, polyethylene or polypropylene.
6. The organic light emitting display of claim 1, wherein the
inorganic layer is formed of one of In.sub.2O.sub.3, SnO.sub.2, ITO
(Indium Tin Oxide), SiO.sub.2 Al.sub.2O.sub.3, TiO.sub.2,
In.sub.2O.sub.3, SnO.sub.2, SiN, SiC, or SiON.
7. A manufacturing method of an organic light emitting display
including: forming a plurality of light emitting areas and a
plurality of bank portions on a substrate, contiguous light
emitting areas having a corresponding bank portion therebetween,
wherein each of the bank portions are formed in a recess shape
between contiguous light emitting areas; and forming an
encapsulation layer covering the light emitting areas and the bank
portions by uniformly covering the bank portions and the light
emitting areas with an organic layer, and forming an inorganic
layer to a greater thickness on the light emitting areas than the
bank portions.
8. The manufacturing method of claim 7, wherein the forming of the
inorganic film includes: forming a first inorganic film on the
organic layer substantially uniformly; and forming a second
inorganic film substantially only on the first inorganic film above
the light emitting areas.
9. The manufacturing method of claim 7, wherein the forming of the
inorganic film includes: forming a first inorganic film
substantially only on the organic layer above the light emitting
areas; and forming a second inorganic film on the organic layer and
the first inorganic film substantially uniformly.
10. The manufacturing method of claim 8, wherein the recessed shape
results in a progressive reduction of a thickness of each bank
portion on opposing sides forming substantially a V-shaped cut out.
Description
This application claims priority to Korean Patent Application No.
10-2006-0010594, filed on Feb. 3, 2006, and all the benefits
accruing therefrom under 35 U.S.C. .sctn.119, and the contents of
which in its entirety are herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organic light emitting display,
and more particularly, to an organic light emitting display having
an encapsulation layer with an improved structure and a
manufacturing method thereof.
2. Description of the Related Art
Generally, organic light emitting displays include an organic light
emitting diode ("OLED") deposited on a thin film transistor (`TFT`)
of an electric circuit so that a selected emitting layer is emitted
in response to a signal controlled by the TFT.
FIG. 1 shows the typical structure of such an organic light
emitting display. As described above, an OLED 20, including an
anode 21, a light emitting layer 22 and a cathode 23, is deposited
on a TFT 10. The TFT 10 includes a substrate 11, a gate electrode
12, a source region 13, a drain region 14 and a via hole 16.
Therefore, when a voltage is applied to the gate electrode 12, a
current passes through the source region 13 to the drain region 14
via a channel opened in an organic semiconductor region 15. A
current flows to the anode 21, the light emitting layer 22 and the
cathode 23 through the via hole 16. At this time, in the light
emitting layer 22, the action of emitting energy in the form of
light occurs as a result of electric coupling, i.e., as a result
that the light emitting layer 22 is excited by the recombination of
holes and electrons. This light may be a luminous spot
corresponding to one pixel of the display panel.
An encapsulation layer 30 protects the light emitting area OLED 20
from moisture and oxygen. As shown in FIG. 2, the encapsulation
layer 30 has a multi-layered structure in which an inorganic film
32, such as a ceramic, and an organic film 31, such as a polymer,
are alternately deposited. Such a structure is disclosed in U.S.
Pat. No. 6,268,695. The organic film 31 can be composed of either
of acrylic, methacrylic, polyester, polyethylene terephthalate,
polyethylene, or polypropylene, etc. The inorganic film 32 can be
composed of one of In.sub.2O.sub.3, SnO.sub.2, ITO (Indium Tin
Oxide), SiO.sub.2, Al.sub.2O.sub.3, TiO.sub.2, In.sub.2O.sub.3,
SnO.sub.2, SiN, SiC, SiON, etc. In this multi-layered structure,
the inorganic film 32 prevents the penetration of oxygen and
moisture and the organic film 31 provides flexibility.
The total number of layers should be at least 10 to enable the
multi-layered structure, in which the organic film 31 and inorganic
film 32 are alternately deposited, to properly perform the hermetic
sealing and protection functions. That is, as described above, the
inorganic film 32 mainly prevents the penetration of oxygen and
moisture. If the thickness of the inorganic film 32 is increased,
the hermetic sealing protection improves, but the flexibility is
drastically decreased. As is well known, the organic light emitting
display aims at being as flexible as paper that can be rolled and a
decrease in flexibility is a drawback of the article. Therefore, it
is preferable to include a plurality of thin inorganic films 32
between the organic films 31 with good flexibility so that the
organic light emitting display has both flexibility and hermetic
sealing protection. In addition, at least 10 inorganic films have
to be deposited to reliably prevent the permeation of moisture and
oxygen.
Because many layers have to be deposited, the manufacturing process
is very complicated. In particular, since the encapsulation layer
30 is made by laminating at least 10 times, the overall
manufacturing process is complicated and productivity is low.
BRIEF SUMMARY OF THE INVENTION
Exemplary embodiments of the present invention provide an improved
organic light emitting display and a manufacturing method of
forming an encapsulation layer having proper flexibility and
sealing ability.
An exemplary embodiments of the present invention includes an
organic light emitting display including: a plurality of light
emitting areas between bank portions on a substrate; and
an encapsulation layer covering the light emitting areas and bank
portions, wherein the encapsulation layer comprises: an organic
layer uniformly covering the bank portions and the light emitting
areas; and an inorganic layer formed thicker on the light emitting
areas than on the bank portions.
According to an exemplary embodiment of the present invention, an
inorganic layer of an organic light emitting display comprises: a
first inorganic film substantially uniformly deposited on the
organic layer; and a second inorganic film deposited substantially
only on the first inorganic film above the light emitting
areas.
In exemplary embodiments, the bank portions have a recessed shape
and are disposed between the light emitting portions.
Moreover, exemplary embodiments of the present invention include a
manufacturing method of the organic light emitting display. The
method includes: forming a plurality of light emitting areas
between bank portions on a substrate; and forming an encapsulation
layer covering the light emitting areas and the bank portions by
uniformly covering the bank portions and the light emitting areas
with an organic layer, and forming an inorganic layer to a greater
thickness on the light emitting areas than the bank portions.
The forming of the inorganic film includes: forming a first
inorganic film on the organic layer substantially uniformly; and
forming a second inorganic film substantially only on the first
inorganic film above the light emitting areas.
In exemplary embodiments, the bank portions are formed in a recess
shape between the light emitting areas.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
FIG. 1 is a cross-sectional view of a conventional organic light
emitting display;
FIG. 2 is a cross-sectional enlarged view of an encapsulation layer
of the organic light emitting display illustrated in FIG. 1;
FIG. 3 is a cross-sectional view of an exemplary embodiment of an
organic light emitting display according to the present
invention;
FIGS. 4A through 4C are cross-sectional views illustrating a method
of forming an encapsulation layer of the organic light emitting
display shown in FIG. 3; and
FIG. 5 is a cross-sectional view of another exemplary embodiment of
an organic light emitting display according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more fully
with reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown. This invention may,
however, be embodied in many different forms and should not be
construed as limited to the exemplary embodiments set forth herein.
Rather, these embodiments are provided so that this disclosure will
be thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. In the drawings, lengths and
sizes of layers and regions may be exaggerated for clarity.
It will be understood that when an element or layer is referred to
as being "on" another element or layer, the element or layer can be
directly on another element or layer or intervening elements or
layers. In contrast, when an element is referred to as being
"directly on" another element or layer, there are no intervening
elements or layers present. Like numbers refer to like elements
throughout. As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
It will be understood that, although the terms first, second,
third, etc., may be used herein to describe various elements,
components, regions, layers and/or sections, these elements,
components, regions, layers and/or sections should not be limited
by these terms. These terms are only used to distinguish one
element, component, region, layer or section from another region,
layer or section. Thus, a first element, component, region, layer
or section discussed below could be termed a second element,
component, region, layer or section without departing from the
teachings of the present invention.
Spatially relative terms, such as "below" or "lower" and the like,
may be used herein for ease of description to describe the
relationship of one element or feature to another element(s) or
feature(s) as illustrated in the figures. It will be understood
that the spatially relative terms are intended to encompass
different orientations of the device in use or operation, in
addition to the orientation depicted in the figures. For example,
if the device in the figures is turned over, elements described as
"below" other elements or features would then be oriented "above"
the other elements or features. Thus, the exemplary term "below"
can encompass both an orientation of above and below. The device
may be otherwise oriented (rotated 90 degrees or at other
orientations) and the spatially relative descriptors used herein
interpreted accordingly.
The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the invention. As used herein, the singular forms "a", "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
Embodiments of the invention are described herein with reference to
cross-section illustrations that are schematic illustrations of
idealized embodiments (and intermediate structures) of the
invention. As such, variations from the shapes of the illustrations
as a result, for example, of manufacturing techniques and/or
tolerances, are to be expected. Thus, embodiments of the invention
should not be construed as limited to the particular shapes of
regions illustrated herein but are to include deviations in shapes
that result, for example, from manufacturing.
For example, an implanted region illustrated as a rectangle will,
typically, have rounded or curved features and/or a gradient of
implant concentration at its edges rather than a binary change from
implanted to non-implanted region. Likewise, a buried region formed
by implantation may result in some implantation in the region
between the buried region and the surface through which the
implantation takes place. Thus, the regions illustrated in the
figures are schematic in nature and their shapes are not intended
to illustrate the actual shape of a region of a device and are not
intended to limit the scope of the invention.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
FIG. 3 is a cross-sectional view of an exemplary embodiment of an
organic light-emitting display according to the present
invention.
Referring to FIG. 3, in the organic light emitting display of the
present exemplary embodiment, an OLED 200 is deposited on a TFT
layer 100. The OLED 200 includes an anode 210, a light-emitting
layer 220 and a cathode 230. The TFT layer 100 includes a substrate
110, a gate electrode 120, a source region 130, a drain region 140
and a via hole 160. When a voltage is applied to the gate electrode
120, a current flows through the source region 130 to the drain
region 140 via a channel formed in an organic semiconductor region
150. The current continues to the anode 210, the light emitting
layer 220 and the cathode 230 through the via-hole 160, and light
is produced and emitted through an encapsulation layer 300.
A bank portion 240 partitioning light emitting areas of the OLED
200 does not have a protruding structure, but is recessed. This
recessed shape results in a progressive reduction of the thickness
of the bank portion 240 on opposing sides forming substantially a
V-shaped cut out, and thus the flexibility of the bank portion 240
is improved. That is, in the organic light emitting area
corresponding to anode 210, light-emitting layer 220 and cathode
230 of OLED 200, the encapsulation layer 300 is thick as explained
below, and thus it enhances sealing. The bank portion 240, which is
a non-luminous portion, is as thin as possible to enhance
flexibility. In other words, in the conventional structure, the
flexibility and sealing properties are provided throughout the
entire encapsulation layer 300, but in the present invention, the
flexibility is focused on the bank portion 240 and a sealing
ability is focused on the lighting emitting area of the OLED
200.
To this end, the thickness of the encapsulation layer 300 is
different in the bank portion 240 and in the light emitting area
corresponding to the anode 210, light-emitting layer 220 and
cathode 230 of the OLED 200. FIGS. 4A through 4C illustrate a
method of forming the encapsulation layer 300. First, as shown in
FIG. 4A, an organic layer 310 with good flexibility is uniformly
formed on the bank portion 240 and OLED 200. The organic layer 310
can be formed of one of acrylic, methacrylic, polyester
polyethylene terephthalate, polyethylene, polypropylene, for
example, but is not limited thereto, and can be formed by
sputtering or evaporation.
Subsequently, an inorganic layer 320 having a sealing ability is
formed. The inorganic layer 320 is formed in two (2) steps. First,
as shown in FIG. 4B, a first inorganic film 320a is uniformly
formed on the organic layer 310. The inorganic layer 320 can be
formed of one of In.sub.2O.sub.3, SnO.sub.2, ITO (Indium Tin
Oxide), SiO.sub.2, Al.sub.2O.sub.3, TiO.sub.2, In.sub.2O.sub.3,
SnO.sub.2, SiN, SiC, SiON, for example, but is not limited thereto,
and can be formed by sputtering or evaporation.
Then, a second inorganic film 320b is formed substantially only on
the OLED 200 (e.g., the second inorganic film 320b is not formed in
the recess or V cut outs of the bank portions 240). That is, the
penetration of foreign materials like moisture and oxygen has to be
prevented in the OLED 200. Therefore, the second inorganic film
320b is formed as a thick layer on the OLED 200 in order to improve
sealing. The second inorganic film 320b is not formed on the bank
portion 240, and thus, the organic light emitting display has good
flexibility. The film is selectively formed by using a patterning
process like photolithography or by using a mask.
A conventional encapsulation layer, as mentioned above, is bent as
a whole because the encapsulation layer is formed having a constant
thickness over the light emitting area and the bank portion 240.
However, in the present embodiment, while the light emitting area
is not bent much due to the thick inorganic layer 320, the bank
portion 240 between the light emitting areas is flexibly bent and
deformed. Therefore, the light emitting area corresponding to the
anode 210, light-emitting layer 220 and cathode 230 of the OLED 200
and the bank portion 240 have the role of flexibility and sealing,
respectively. In this case, there is no need for flexibility in the
light emitting area. Therefore, the second inorganic film 320b can
be formed to be quite thick. That is, conventionally, the inorganic
film is formed repeatedly between the organic layers so as to
provide flexibility. However, in the present invention, the organic
layer 320 is formed in the light emitting area to a thickness
required to obtain a desired sealing ability because there is
little need for flexibility. Therefore, productivity can be
improved while simplifying the manufacturing process.
FIG. 5 is a cross-sectional view of another exemplary embodiment of
an organic light emitting display according to the present
invention. In the drawings, like reference numerals denote elements
performing like functions.
In the present exemplary embodiment of FIG. 5, like in the previous
exemplary embodiment of FIGS. 4A-4C, the inorganic layer 320 is
thick on the light emitting area 200 and provides a sealing
property, whereas the inorganic layer 320 is thin on the bank
portion 240 so as to improve flexibility.
However, the process of forming the first and second inorganic
films 320a and 320b of the inorganic layer 320 is different in the
present exemplary embodiment. In the present exemplary embodiment,
the first inorganic film 320a is formed substantially only on the
light emitting area 200 after forming the organic layer 310 and the
second inorganic film 320b is substantially uniformly formed on the
first inorganic film 320a.
In this case, the light emitting area corresponding to OLED 200
does not have the burden of contributing to the flexibility.
Therefore, the first inorganic film 320a can be formed to a
sufficient thickness to obtain desired sealing properties. As a
result, since there is no need to repeatedly deposit the thin
inorganic film between the organic films as in the conventional
art, the manufacturing process is simpler and productivity can be
greater than in the conventional art.
According to the present invention, as described above, when
manufacturing the encapsulation layer of the organic light emitting
display, the inorganic layer is thick on the light emitting area in
which a sealing ability is required and the bank portion is thin in
order to provide flexibility. Therefore, the present invention can
be formed more easily than a conventional device in which the
organic layer and inorganic layer are alternately formed at least
10 times.
While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *